Integrators have application in a wide range of electronic circuits, for example, analogue-to-digital converters, particularly sigma-delta analogue-to-digital converters, digital-to-analogue converters, and filters, particularly loop filters in control loops. In many electronic devices utilising such circuits, and particularly in mobile electronic devices, low voltage operation and low power consumption is important. Adaptation of conventional circuits to low power operation can cause undesirable restriction of the permitted range of signal voltage swing and undesirable increase in power consumption, due, for example, to the need to use folded cascoding for increasing gain. Some circuits for reducing power consumption are impractical for use at low voltages. Therefore, there is a need for an improved integrator.